A curved micro-ceramic glass plate and its preparation method and application

Abstract

The present invention relates to the technical field of curved microcrystalline panels, and more specifically, to a curved microcrystalline glass plate, its preparation method, and its application. The roughness of the inner and outer surfaces of the curved microcrystalline glass plate is both ≤0.06μm; the radial unevenness A of the curved microcrystalline glass plate is ≤0.4%, where A = h / L×100%; and the axial unevenness B of the curved microcrystalline glass plate is ≤0.4%, where B = d / L×100%. The curved microcrystalline glass plate provided by the present invention has a flat and smooth surface, can avoid optical scattering, and meets visibility requirements. It also has good flatness, low radial and axial unevenness, and no "warping" phenomenon or obvious visual distortion.

Description

Technical Field

[0001] The present invention relates to the technical field of curved microcrystalline panels, and in particular to a curved microcrystalline glass plate and a preparation method and application thereof. Background Art

[0002] LAS glass-ceramics (hereinafter referred to as glass-ceramics) has a primary crystalline phase composition of Li₂O-Al₂O₃-SiO₂. Its low expansion, high strength, and adjustable light transmittance make it widely used in various heating applications, particularly in stovetops and kitchen appliance covers, which are key applications. The mainstream glass-ceramics production technology is the melt glass calendering method, which produces flat glass-ceramics. Glass-ceramics can be categorized by their color properties into tinted glass-ceramics, transparent glass-ceramics, and white glass-ceramics. A 4mm-thick glass-ceramic panel made from transparent glass-ceramics boasts a visible light transmittance exceeding 70%, and its low expansion, high strength, and excellent chemical stability make it an ideal material for applications such as high-temperature observation windows and fireplaces. Due to the limitations of the calendering production process, early fireplace designs were primarily square to accommodate flat glass-ceramic panels. With the advent of cylindrical fireplaces, which offer a novel and unique appearance, the production of curved glass-ceramics panels has become increasingly critical. To enhance visibility, curved micro-crystalline panels often require smooth and flat surfaces on both sides, with a roughness of Ra ≤ 0.06μm, to prevent optical scattering. Furthermore, curved micro-crystalline panels are typically mounted within specific metal frames in practical applications, placing strict demands on dimensional tolerances and flatness.

[0003] The existing production process for curved microcrystalline panels is generally gravity molding. That is, first prepare a concave mold, place the flat base glass panel (base glass refers to the uncrystallized microcrystalline panel) horizontally in the concave mold, and heat it to the softening temperature to keep it warm. Under the action of gravity, the base glass plate deforms until it fits the mold, achieving the arc molding effect. Subsequently, the temperature is continued to increase, and crystallization occurs inside the curved plate to obtain curved microcrystalline glass. This method is particularly suitable for small curved microcrystalline panels with a small central angle. Among them, the mold is the key equipment of the gravity molding method. The dimensions of the curved microcrystalline glass, such as the inner radius and tolerance, are directly determined by the mold.

[0004] In actual production, molds are primarily made of heat-resistant iron-based alloys. However, the inherently high thermal expansion coefficient of metals makes them susceptible to torsional deformation after repeated thermal cycling, causing the curved microcrystalline panels that adhere to their inner walls to undergo similar torsional deformation. This leads to a noticeable "warping" phenomenon when inverted. For example, when using an iron-based mold to produce a curved microcrystalline panel with an inner diameter R (the iron-based mold is curved, and R refers to the inner diameter of the arc) of 260mm, a central angle of 60°, and a length of 300mm, the radial unevenness can reach as high as 1.67%. Here, radial unevenness A = h / L × 100%. When the curved microcrystalline panel is placed with its opening facing downward on a horizontal surface, three of its vertices are in contact with the horizontal plane, and one vertex is at a distance h from the horizontal plane. L is the axial length of the curved microcrystalline panel. This means that when a 300mm long curved microcrystalline panel is inverted, the remaining vertex can be as high as 5mm above the horizontal plane, completely failing to meet the assembly requirements for fireplace observation windows.

[0005] In addition, for curved microcrystalline plates with a central angle greater than 114°, when the length of the original microcrystalline plate exceeds 2R (R is the inner diameter of the arc of the concave mold), it cannot be simply prepared using a concave mold.

[0006] In response to the above problems, the patent application number DE2001102576 discloses a method for forming a large arc (>114°) microcrystalline plate. In response to the situation where the length of the microcrystalline original plate exceeds the concave mold, the patent discloses a set of forming devices, that is, cylindrical rotating rollers are set on the top of the left and right sides of the concave mold to help the flat microcrystalline original plate to continue to descend and form under the action of gravity. During the softening stage, the base glass in the center softens and falls, continuously driving the base glass on the support bars on both sides of the concave mold to move toward the concave mold, and finally forming an arc shape that falls as a whole into the concave mold. However, the structure of the device is obviously more complicated. At high temperatures of 800 to 900°C, it is obviously difficult to easily solve the problems of fixing the rotating rollers and keeping the rotation process horizontal. In addition, the microcrystalline original plate is always in contact with the support bars and rotating rollers during the softening process, and there is relative movement, which easily forms scratches on the surface of the microcrystalline original plate. These scratches require an additional polishing step to remove, but polishing curved glass is much more complicated than polishing flat glass. Furthermore, the inherent small-batch, multi-specification nature of curved glass products makes the process of forming first and then polishing extremely uneconomical. Furthermore, this approach struggles to overcome the problem of twisting of the microcrystalline original plate during the softening process. Various disturbances during the production process can easily cause the microcrystalline original plate to rotate at a small angle when it falls, resulting in high radial unevenness. Therefore, a subsequent cutting step is required to trim the arc produced by the above method so that the four vertices are on the same horizontal plane.

[0007] Furthermore, neither the aforementioned patent nor existing applications mention axial flatness B, where B = d / L × 100%, where L is the axial length of the curved microcrystalline panel. When the curved microcrystalline panel is placed on a horizontal surface with its opening facing downward, the maximum distance between the downward-bending arc formed by the top of the curved microcrystalline panel and the line connecting the midpoints of the two curved edges of the curved microcrystalline panel is d. In reality, during the crystallization process, the original microcrystalline panel is very likely to form an inward arch along the axial direction. Although this deformation does not affect the assembly of the curved microcrystalline glass panel in applications such as fireplaces, it does cause significant visual distortion near the curved edge, so the axial flatness B also needs to be controlled at a low level.

[0008] In order to achieve a smooth, distortion-free surface for the curved microcrystalline panel, with excellent flatness and adaptability to tooling, conventional preparation methods often require complex subsequent processing procedures to further polish or cut the formed curved microcrystalline glass to the designed size.

[0009] In view of this, the present invention is proposed. Summary of the Invention

[0010] The first objective of the present invention is to provide a curved glass-ceramic panel with a smooth surface, with both inner and outer surface roughness Ra ≤ 0.06 μm. This prevents optical scattering and meets visibility requirements. Furthermore, the panel exhibits excellent flatness, low radial and axial unevenness, no "warping," and no noticeable visual distortion along the curved edges. This overcomes the existing problems with curved glass-ceramic panels, which struggle to meet a double-sided roughness requirement of ≤ 0.06 μm and exhibit poor radial and axial flatness.

[0011] The second purpose of the present invention is to provide a method for preparing a curved microcrystalline glass plate, which adopts the steps of first polishing and then forming and crystallizing. It can be formed in one step to directly obtain the required curved microcrystalline panel with a smooth surface and excellent flatness, without the need for subsequent mechanical processing such as polishing, trimming, chamfering, etc. of the curved panel.

[0012] The third object of the present invention is to provide applications of the curved glass-ceramic plate in the fields of architecture and decoration.

[0013] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are adopted:

[0014] The present invention first provides a curved glass-ceramic plate, wherein the roughness of the inner surface of the curved glass-ceramic plate is ≤0.06 μm, and the roughness of the outer surface of the curved glass-ceramic plate is ≤0.06 μm;

[0015] The shape of the curved glass-ceramic plate is an arc;

[0016] The radial unevenness A of the curved glass-ceramic plate is ≤ 0.4%, where A = h / L × 100%. When the curved glass-ceramic plate is placed on a horizontal plane with its opening facing downward, three vertices of the curved glass-ceramic plate are in contact with the horizontal plane, and the distance from the other vertex to the horizontal plane is h. L is the length of the curved glass-ceramic plate in the axial direction. The units of h and L are the same.

[0017] The axial unevenness B of the curved microcrystalline glass plate is ≤0.4%, where B = d / L×100%; when the curved microcrystalline glass plate is placed on a horizontal plane with its opening facing downward, the top of the curved microcrystalline glass plate bends downward along the axial direction of the curved microcrystalline glass plate to form a curved arc, and the maximum distance between the curved arc and the line connecting the midpoints of the two curved edges of the curved microcrystalline glass plate is d; L is the length of the curved microcrystalline glass plate along the axial direction; the units of d and L are the same.

[0018] Furthermore, the thermal expansion coefficient of the curved glass-ceramic plate at a temperature of 40 to 700° C. is less than 0.5 ppm / ° C.

[0019] The present invention further provides a method for preparing the curved glass-ceramic plate, comprising the following steps:

[0020] Obtain a double-sided polished flat microcrystalline original plate;

[0021] The double-sided polished flat microcrystalline original plate is placed on a refractory material mold and then subjected to heat treatment for shaping and crystallization to obtain the curved microcrystalline glass plate.

[0022] Furthermore, the vertices of the double-sided polished flat microcrystalline original plate are chamfered and / or rounded, and the four sides of the double-sided polished flat microcrystalline original plate are chamfered and / or rounded.

[0023] Furthermore, the material of the flat-plate microcrystalline original plate includes LAS microcrystalline glass.

[0024] Furthermore, the refractory material in the refractory mold includes at least one of a zirconium refractory material, a corundum refractory material, a magnesia refractory material, a calcium-magnesia refractory material and a silicon refractory material.

[0025] Furthermore, the thickness of the refractory material mold is ≤15 mm.

[0026] Furthermore, the roughness of the inner surface of the refractory material mold is 0.05-4.00 μm.

[0027] Furthermore, the central angle of the curved glass-ceramic plate is greater than 114°.

[0028] Furthermore, the shape of the refractory mold is arc-shaped; the refractory mold is respectively connected to auxiliary side edges on two sides along the axial direction thereof, and the auxiliary side edges are in the shape of a flat plate. The refractory mold is fixedly connected or detachably connected to the two auxiliary side edges. When the refractory mold is placed with the opening facing upward, the angle α between the auxiliary side edges and the horizontal plane satisfies: α>(21750-2490000 / θ) 1 / 2 , where θ is the central angle of the curved glass-ceramic plate, in degrees.

[0029] The present invention also provides applications of the curved glass-ceramic plate in the fields of architecture and decoration.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The curved glass-ceramics plate provided by the present invention has a smooth surface and good flatness.

[0032] (2) The curved glass-ceramic plate provided by the present invention has no scratches on the surface.

[0033] (3) The curved microcrystalline glass plate provided by the present invention has a central angle greater than 114° and a low thermal expansion coefficient.

[0034] (4) The method for preparing the curved microcrystalline glass plate provided by the present invention is to first polish and then form and crystallize, so as to produce a low-expansion curved microcrystalline glass plate with a smooth surface and good flatness.

[0035] (5) The method for preparing the curved microcrystalline glass plate provided by the present invention is to polish first and then form and crystallize, which has high production efficiency and high yield. In addition, the method of polishing first is used to industrially polish the flat plate, which has high polishing quality and high polishing efficiency. In addition, the plate surface is basically not broken during the polishing process, and the plate loss is small.

[0036] (6) The method for preparing the curved microcrystalline glass plate provided by the present invention uses refractory materials instead of traditional metal alloy materials to manufacture molds. The refractory material molds can be used for a long time without deformation and can be recycled many times.

[0037] (7) The method for preparing the curved microcrystalline glass plate provided by the present invention can prepare a curved microcrystalline plate with a central angle greater than 114° by setting auxiliary side edges on both sides of the mold.

[0038] (8) The method for preparing the curved microcrystalline glass plate provided by the present invention can improve the axial flatness of the curved microcrystalline glass plate by controlling the thickness of the refractory material mold.

[0039] (9) The method for preparing the curved microcrystalline glass plate provided by the present invention can ensure that no scratches are generated on the surface of the microcrystalline original plate during the falling process by controlling the angle α between the auxiliary side and the horizontal plane, thereby ensuring that the surface of the curved microcrystalline glass plate is free of scratches. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0041] Figure 1 A schematic structural diagram of the curved glass-ceramic plate provided by the present invention;

[0042] Figure 2 This is a schematic diagram of the structure of the curved glass-ceramic plate provided by the present invention when the opening is placed downward;

[0043] Figure 3 Another schematic diagram of the structure of the curved glass-ceramic plate provided by the present invention when the opening is placed downward;

[0044] Figure 4 A schematic structural diagram of a refractory material mold with auxiliary side edges provided by the present invention;

[0045] Figure 5 This is a schematic structural diagram of placing a double-sided polished flat microcrystalline original plate horizontally on a refractory material mold in Example 1 provided by the present invention;

[0046] Figure 6 A linear expansion coefficient curve diagram of the curved microcrystalline panel prepared in Example 1 provided by the present invention;

[0047] Figure 7 This is a visible light transmittance curve of the curved microcrystalline panel prepared in Example 1 provided by the present invention. DETAILED DESCRIPTION

[0048] The technical scheme of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. Those who do not specify specific conditions in the embodiments are carried out according to normal conditions or the conditions recommended by the manufacturer. Those whose reagents or instruments are not specified by the manufacturer are conventional products that can be purchased commercially.

[0049] Unless otherwise specified, in the present invention, terms such as "first aspect," "second aspect," "third aspect," and "fourth aspect" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor as implicitly indicating the importance or quantity of the technical features indicated. Furthermore, terms such as "first," "second," "third," and "fourth" serve only as non-exhaustive enumeration and description, and should not constitute closed-ended limitations on quantity.

[0050] Unless otherwise specified, the terms "include" and "comprising" used in the present invention may be open-ended or closed-ended. For example, "include" and "comprising" may mean that other components not listed may also be included or that only the listed components are included.

[0051] Unless otherwise specified, in the present invention, "one or more" or "at least one" refers to any one, any two, or any two or more of the listed items. Among them, "several" refers to any two or any two or more.

[0052] In a first aspect, the present invention provides a curved microcrystalline glass plate, wherein the roughness of the inner surface of the curved microcrystalline glass plate is ≤0.06μm, including but not limited to any point value of 0.05μm, 0.04μm, 0.03μm, 0.02μm, 0.01μm or a range value between any two of them; the roughness of the outer surface of the curved microcrystalline glass plate is ≤0.06μm, including but not limited to any point value of 0.05μm, 0.04μm, 0.03μm, 0.02μm, 0.01μm or a range value between any two of them.

[0053] See also Figure 1As shown, the curved glass-ceramic plate is in an arc or arch shape. It is understood that the curved glass-ceramic plate includes two curved edges and two straight edges. The curved glass-ceramic plate includes four vertices, i.e., the intersections of the curved edges and the straight edges. The vertices can be right angles, chamfered angles, or rounded angles, preferably chamfered angles or rounded angles, i.e., the curved edges and the two straight edges are trimmed to be chamfered or rounded.

[0054] The radial unevenness A of the curved glass-ceramic plate is ≤ 0.4%, including but not limited to any one of 0.35%, 0.3%, 0.25%, 0.2%, 0.15%, 0.1%, 0.05% or any range between two values. Wherein, A = h / L × 100%. Figure 2 As shown, when the curved glass-ceramic plate is placed on a horizontal plane with its opening facing downward (the curved edge is in an n-shape), three vertices of the curved glass-ceramic plate are in contact with the horizontal plane, and the distance from the other vertex to the horizontal plane is h. L is the length of the curved glass-ceramic plate along the axial direction. The units of h and L are the same.

[0055] The axial unevenness B of the curved glass-ceramic plate is ≤ 0.4%, including but not limited to any one of 0.35%, 0.3%, 0.25%, 0.2%, 0.15%, 0.1%, 0.05% or any range between two values. Wherein, B = d / L × 100%. Figure 3 As shown, when the curved microcrystalline glass plate is placed on a horizontal plane with its opening facing downward (the curved edge is n-shaped at this time), along the axial direction of the curved microcrystalline glass plate, the top end of the curved microcrystalline glass plate bends downward to form a curved arc (that is, the outer side of the top end of the curved microcrystalline glass plate is concave), and the maximum distance between the curved arc and the line connecting the midpoints of the two curved edges of the curved microcrystalline glass plate is d; L is the length of the curved microcrystalline glass plate along the axial direction; wherein, the units of d and L are the same.

[0056] In some specific embodiments, a straight line is drawn through the midpoints of the two curved sides of the curved glass-ceramic plate, or a calibrated straight metal tube is placed so that the ends of the metal tube respectively contact the midpoints of the two curved sides of the curved glass-ceramic plate. Since the top of the curved glass-ceramic plate is concave downward, there is a certain distance between the concave part and the straight line or the metal tube. The maximum gap between the concave part and the straight line or the metal tube is d, and this distance d can be measured using a feeler gauge that complies with GB / T 22523. The feeler gauge is a prefabricated steel sheet, wherein the thickness of the steel sheet is an integer multiple of 0.05 mm, such as 0.05 mm, 0.10 mm, 0.15 mm, etc.

[0057] The curved micro-ceramic glass plate provided by the present invention has a flat and smooth surface, and the roughness of both the inner and outer surfaces is ≤0.06 μm, which can avoid optical scattering and has good flatness.

[0058] In the present invention, the roughness is measured using Mitutoyo SJ-210 according to ISO 1997, and λc is set to 2.5.

[0059] In some specific embodiments, the thermal expansion coefficient of the curved glass-ceramic plate at a temperature of 40-700°C is less than 0.5 ppm / °C. The curved glass-ceramic plate provided by the present invention has the advantage of low thermal expansion and can withstand instantaneous temperature differences of up to 750°C. Specifically, the curved glass-ceramic plate was placed in a muffle furnace at 780°C and maintained at a constant temperature for at least 30 minutes. After removal, it was immediately immersed in room temperature water and completely submerged without breaking or visible cracks.

[0060] In a second aspect, the present invention provides a method for preparing the curved glass-ceramic plate, comprising the following steps:

[0061] First, a double-sided polished flat microcrystalline original plate is obtained.

[0062] Among them, the microcrystalline original plate refers to the glass plate that is rolled into a flat shape after being melted in a glass melting furnace. It is not crystallized and can also be called basic glass.

[0063] The double-sided polished flat microcrystalline original plate is then placed on a refractory mold and placed in a heating furnace for heat treatment to form and crystallize the plate. After cooling, the curved microcrystalline glass plate is obtained. The refractory mold does not deform at high temperatures.

[0064] It is understood that during the heat treatment process, the double-sided polished flat microcrystalline substrate is heated and softened. Under the action of gravity, the center of gravity of the microcrystalline substrate continues to drop, eventually clinging to the refractory mold, forming an arc. The heat treatment temperature, time, and heating rate can be any parameters commonly used in the art, and the present invention is not limited thereto.

[0065] The preparation method of the curved microcrystalline glass plate provided by the present invention adopts the steps of first polishing and then forming and crystallizing, which can effectively control the roughness of the inner and outer surfaces of the curved microcrystalline glass plate to be ≤0.06μm, and the roughness hardly changes before and after heat treatment. The low-expansion curved microcrystalline glass plate prepared by this method has a smooth surface, good flatness, and no surface scratches.

[0066] The preparation method of the curved microcrystalline glass plate provided by the present invention is to polish first and then form and crystallize, which can save labor time. In addition, the method of polishing first makes it extremely easy to industrially polish the flat plate, and the breakage rate during the polishing process is low and the polishing quality is high.

[0067] At the same time, the preparation method of the curved micro-ceramic glass plate provided by the present invention is simple, and is formed in one step without the need for subsequent grinding, cutting, polishing and other processes.

[0068] In addition, the present invention uses refractory materials instead of traditional metal alloy materials to manufacture molds. Molds made of refractory materials can be used for a long time without deformation and can be recycled many times. This solves the problem of "warping corners" easily occurring in the existing technology using metal materials.

[0069] In some specific embodiments, the vertices of the double-sided polished flat microcrystalline original plate are chamfered and / or rounded.

[0070] In some specific embodiments, the four edges of the double-sided polished flat microcrystalline original plate are trimmed to be chamfered and / or rounded.

[0071] That is, the appearance requirements of the corners and edges of the flat-plate microcrystalline original plate are met, and corresponding machining treatment is performed when the microcrystalline original plate is prepared.

[0072] In some specific embodiments, the method for obtaining a double-sided polished flat microcrystalline original plate includes: calculating the size of the flat microcrystalline original plate corresponding to the curved microcrystalline glass plate, taking into account the volume shrinkage during the crystallization process, and the size of the flat microcrystalline original plate is preferably slightly larger than the size of the final curved microcrystalline glass plate product. Take a larger flat microcrystalline original plate, polish it on both sides, and cut it to the designed flat plate size. It is understandable that it can be polished first and then cut, or it can be cut first and then polished. Then, the four edges are trimmed so that the ends of the four edges are chamfered or rounded.

[0073] In some specific embodiments, the double-sided polished flat microcrystalline original plate is placed horizontally, and a level meter can be used to calibrate the horizontal placement of the double-sided polished flat microcrystalline original plate.

[0074] In some specific embodiments, the material of the flat-type microcrystalline original plate includes LAS microcrystalline glass (i.e., flat-type LAS microcrystalline glass original plate), but is not limited to this. The preparation method of the curved microcrystalline glass plate provided by the present invention can also be applied to other types of microcrystalline glass panels that need to be prepared into a curved shape.

[0075] Among them, the glass transition point of the flat LAS microcrystalline glass original plate, that is, the basic glass without crystallization, is about 700℃, while the glass-ceramic glass after crystallization has a glass transition point as high as above 900℃, that is, the softening temperature is also above 900℃, so it is difficult to crystallize LAS microcrystalline glass first and then bend it into shape.

[0076] In some specific implementations, the heat treatment specifically includes: preheating first, then softening and nucleation, and then crystallization.

[0077] In some specific embodiments, during the preheating process, the heating rate is 2 to 30 K / min, and the temperature of the heating furnace is raised from room temperature to the softening temperature Ts of the flat microcrystalline substrate. The heating rate can be as high as possible while ensuring that the flat microcrystalline substrate and the refractory mold do not rupture due to thermal expansion.

[0078] In some specific embodiments, during the softening and nucleation process, an arc-shaped microcrystalline original plate is formed. The softening temperature Ts is 20 to 110°C above the Tg point (glass transition point), generally 710 to 820°C, and is kept warm for 10 to 60 minutes. The softening process can be constant temperature or heated. The total holding time varies depending on the difficulty of forming the microcrystalline panel. The arc-shaped plate with a larger central angle is more significantly affected by gravity, and the time required for softening may be shorter. If the Ts temperature is too low, the viscosity of the glass is high, and it falls slowly under the action of gravity, which takes too long and may even not bend in place. If Ts is too large, it is easy to cause crystal growth and increase the degree of crystallinity. The significant effect of increased crystallinity is that the viscosity increases, and the glass is difficult to soften and deform, which also leads to incomplete bending. Incomplete bending here refers to the final formed microcrystalline panel, where the lowest point on the outer side of the arc surface is more than 1 mm away from the inner surface of the mold, and there is a gap that is obvious to the naked eye. The temperature in this step is below Tc but above Tg, so the softening temperature generally coincides with the nucleation temperature, and nucleation is completed during the softening process. This softening process can achieve good axial flatness. That is, the curved microcrystalline original plate formed after high-temperature softening can usually fit the mold tightly.

[0079] In some specific embodiments, a curved microcrystalline glass plate is formed after the crystallization. During the crystallization process, the temperature is continued to rise to the crystallization temperature Tc, with a heating rate of 2 to 15K / min. The Tc temperature is generally in the range of -30 to +100°C of the Tp point temperature. The Tp temperature is obtained by measuring the thermal effect of the microcrystalline original plate, and conventional detection equipment such as DSC and DTA detection are used. The Tc temperature is kept for 10 to 45 minutes, and crystal growth is achieved in this process. The temperature range for crystallization of LAS microcrystalline glass is relatively wide. It can be crystallized not only in the Tc insulation stage, but also in the heating stage before crystallization. Generally, the maximum temperature set is Tp point temperature -30 + 100°C, which is called the crystallization temperature Tc, and is kept warm at this temperature. The heating rate can be 1 to 15K / min, and the maximum value of the heating rate is limited to not causing the microcrystalline glass and refractory mold to break. The holding time is 10 to 45 minutes. Too long a holding time or too high a holding temperature will cause the high quartz crystal phase to transform into the hydrothermal quartz crystal phase, thereby significantly increasing the expansion coefficient; too short a holding time or too low a holding temperature will lead to insufficient crystallization and fail to meet the low expansion performance requirements.

[0080] In some specific embodiments, the refractory material used in the refractory mold includes at least one of a zirconium refractory material, a corundum refractory material, a magnesia refractory material, a calcium-magnesia refractory material, and a silica refractory material.

[0081] In some specific embodiments, the thickness of the refractory mold is ≤15mm, including but not limited to any one of 14mm, 13mm, 12mm, 11mm, 10mm, 8mm, 6mm, 5mm, 3mm, and 2mm, or a range of values ​​between any two of them; preferably 2 to 15mm. Refractory materials have extremely poor thermal conductivity. When a refractory mold is made, if the temperature difference in the transverse direction (with the axial direction of the curved microcrystalline plate as the transverse direction) is large, when the volume shrinks during the crystallization process, it will cause deformation in the axial direction and form an arch toward the center of the circle. The inventors found that the thinner the thickness, the smaller the transverse temperature difference of the refractory mold, and the better the flatness of the microcrystalline panel, especially the axial flatness. However, refractory molds with a thickness of less than 2mm face greater challenges in the mold preparation process, are easily broken during use, and are also easily broken during processing. Therefore, the present invention controls the temperature uniformity of the refractory mold to be better when the thickness of the refractory mold is less than 15mm, and can control the axial unevenness of the refractory mold and the resulting curved microcrystalline glass plate. The present invention solves the problem that the prior art does not consider the axial flatness, resulting in obvious visual distortion near the curved edge.

[0082] In some specific embodiments, the maximum thickness of the refractory material mold is ≤15 mm.

[0083] In some specific embodiments, the thickness of the refractory mold is different at different bends, the thickness at the center of the refractory mold is greater than the thickness at both ends, and the thickness at the center of the refractory mold (the bottom end when the opening is placed upward) is the largest, see Figure 4 As shown, the thickness at both ends is slightly less than that at the center.

[0084] In some specific embodiments, thinner refractory molds are prone to breakage during mold processing or crystallization. At this time, an auxiliary method can be used, that is, two side brackets are designed on the outside of the refractory mold to reduce the phenomenon of breakage during mold processing or crystallization.

[0085] In some specific embodiments, the roughness of the inner surface of the refractory mold is 0.05 to 4.00 μm, including but not limited to any one of 0.05 μm, 0.10 μm, 0.20 μm, 0.30 μm, 0.50 μm, 0.80 μm, 1.00 μm, 2.00 μm, 3.00 μm, and 4.00 μm, or a range of values ​​between any two of them. The present invention uses a polished microcrystalline original plate, which is easily adsorbed with the glass phase in the refractory material during the crystallization process, resulting in damage to the surface of the microcrystalline panel. Increasing the roughness of the inner surface of the refractory mold can avoid this problem. However, the roughness of the inner surface of the refractory mold should not be too large. If it is too large, small particles on the surface of the refractory mold are likely to fall off during the crystallization process, thereby forming defects such as pits and white spots on the surface of the microcrystalline panel.

[0086] In some specific embodiments, the central angle θ of the curved microcrystalline glass plate is greater than 114°, including but not limited to any point value of 115°, 116°, 118°, 120°, 130°, 140°, 160° or a range of values ​​between any two of them.

[0087] In some specific embodiments, the shape of the refractory mold is arc-shaped. The refractory mold is connected to auxiliary side edges on two sides along the axial direction thereof, see Figure 4 As shown, the auxiliary side is in the shape of a plate, and the ends of the auxiliary side are connected to the ends of the refractory mold, wherein the refractory mold and the two auxiliary side are fixedly connected or detachably connected. When the refractory mold is placed with the opening facing upward, the angle α between the auxiliary side and the horizontal plane satisfies the following relationship: α>(21750-2490000 / θ) 1 / 2 , where θ is the central angle of the arc-shaped glass-ceramic plate, i.e., the central angle of the arc, and the unit is degree (°). This ensures that no scratches are generated on the surface of the original glass-ceramic plate during the falling process.

[0088] That is, the auxiliary side can be an integral structure with the refractory mold, or a separate structure fixed into a desired structure by an external bracket.

[0089] By providing auxiliary side edges on both sides of the mold, the present invention can produce curved microcrystalline panels with a central angle greater than 114°. This solves the problem that conventional concave molds are difficult to produce curved microcrystalline panels with a central angle greater than 114° when the base glass length exceeds 2R (R is the inner diameter of the concave mold arc).

[0090] In some specific embodiments, after double-sided polishing, the roughness of both surfaces (ie, the upper surface and the lower surface) of the double-sided polished flat microcrystalline original plate is ≤0.06 μm.

[0091] The roughness of the outer surface (the surface in contact with the refractory mold) and inner surface of the curved glass-ceramic plate prepared by the present invention is almost the same as that of the flat-type glass-ceramic original plate. The heat treatment process hardly causes degradation of the roughness.

[0092] In a third aspect, the present invention provides applications of the curved glass-ceramic plate in the fields of architecture and decoration.

[0093] Among them, the architectural field includes but is not limited to applications in glass curtain walls, wall decoration, etc., and the decorative field includes but is not limited to applications in interior home decoration, artwork production, aquariums and fish tanks, courtyard landscaping, etc.

[0094] The embodiments of the present invention will be described in detail below with reference to the examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention. Where specific conditions are not specified in the examples, the methods were performed according to conventional conditions or the conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments are not specified, they are all commercially available conventional products.

[0095] In each embodiment of the present invention and each comparative example, the roughness was measured using a Mitutoyo SJ-210 according to the ISO 1997 method, with λc set to 2.5.

[0096] Example 1

[0097] This embodiment provides a curved micro-ceramic panel (i.e., a curved micro-ceramic glass plate) having an arc radius R of 300 mm, an arc chord height d of 173.2 mm, an axial length L of 400 mm, and a thickness of 4 mm. The preparation method thereof includes the following steps:

[0098] (1) Take a flat LAS glass-ceramic plate, process it to a thickness of 4.05 mm, and polish it to a roughness of 0.026 μm on both the upper and lower surfaces by double-sided polishing. Then cut it into a rectangle with a size of 696.7 mm × 404 mm, and trim the four edges to make the corners rounded.

[0099] (2) Quartz ceramic refractory material (i.e., silica refractory material) is used to make a refractory mold. The shape of the refractory mold is arc-shaped, with a thickness of ≤8mm. The center of the refractory mold (the bottom end when the opening is placed upward) has the largest thickness of 8mm, and the thickness of the remaining parts is slightly less than 8mm. The arc radius of the refractory mold is 304mm, the center angle of the mold is 180°, and the length of the mold in the axial direction is 450mm, which exceeds the length of the microcrystalline original plate (the length in the axial direction is 405mm) by 45mm. The roughness of the inner surface of the refractory mold is 3.86μm.

[0100] The refractory material mold is respectively connected to auxiliary side edges on its two sides along the axial direction. The auxiliary side edges are flat-plate-shaped. The two auxiliary side edges have the same shape and size. The auxiliary side edges are the same length as the refractory material mold, which is 450 mm. The width of the auxiliary side edges (i.e., the direction extending outward along the opening of the refractory material mold) is 90 mm. The refractory material mold and the two auxiliary side edges are a fixedly connected one-piece structure. When the refractory material mold is placed with the opening facing upward, the angle α between the auxiliary side edges and the horizontal plane is 55°.

[0101] (3) Place the double-sided polished flat microcrystalline original plate obtained in step (1) horizontally on the refractory material mold obtained in step (2), see Figure 5 As shown, it is placed in a heating furnace for heat treatment to be formed and crystallized, and then quickly cooled to room temperature to obtain the curved microcrystalline glass plate, which has an arc shape.

[0102] The heat treatment specifically involves preheating from room temperature to 720°C at a heating rate of 15K / min for approximately 46 minutes. The temperature is then raised to 780°C for 30 minutes at a rate of 2K / min to complete the softening and nucleation process. The temperature is then raised to 880°C at a rate of 5K / min for 20 minutes, followed by a 30-minute hold at 880°C to complete crystallization.

[0103] The linear expansion coefficient curve of the curved microcrystalline panel prepared in this embodiment is shown in FIG. Figure 6 It can be seen that the thermal expansion coefficient of the curved microcrystalline panel prepared in Example 1 at 40-700°C is 0.29 ppm / °C.

[0104] The visible light transmittance curve of the curved microcrystalline panel prepared in this embodiment is shown in FIG. Figure 7 As shown. It can be calculated that the transmittance of the curved microcrystalline panel prepared in Example 1 in the visible light range (400-700nm) is 86.67%. The transmittance is tested according to the method specified in GB / T 2680-1994. The testing equipment is Hunterlab ColorQuest XE, and the visible light detection wavelength range is 400-700nm.

[0105] Example 2 to Example 3

[0106] The differences between Example 2 and Example 3 and Example 1 are shown in Table 1.

[0107] Example 4 to Example 6

[0108] The differences between Example 4, Example 5 and Example 6 and Example 1 are shown in Table 2.

[0109] Example 7

[0110] The preparation method of the curved microcrystalline panel provided in this embodiment is basically the same as that of Example 1, except that the quartz ceramic refractory material is replaced by a corundum ceramic refractory material (ie, a corundum refractory material).

[0111] The thermal expansion coefficient is related to the heat treatment process. The heat treatment process of Examples 2 to 7 is the same as that of Example 1. Therefore, the thermal expansion coefficient of the curved microcrystalline panels produced in Examples 2 to 7 at 40-700°C is basically the same as that of the curved microcrystalline panel in Example 1.

[0112] Light transmittance is related to the heat treatment process and surface roughness. The heat treatment process of Examples 2 to 7 is the same as that of Example 1, and the surface roughness is basically the same as that of Example 1. Therefore, the visible light transmittance of the curved microcrystalline panels obtained in Examples 2 to 7 is basically the same as that of the curved microcrystalline panel in Example 1.

[0113] Comparative Example 1 to Comparative Example 2

[0114] The differences between Comparative Examples 1 and 2 and Example 1 are shown in Table 1. In particular, the maximum thickness of the mold in Comparative Example 1 is 25 mm. In Comparative Example 2, α does not satisfy > (21750-2490000 / θ) 1 / 2 .

[0115] Comparative Example 3 to Comparative Example 4

[0116] The differences between Comparative Examples 3 and 4 and Example 1 are shown in Table 2. The inner surface roughness Ra of the mold in Comparative Example 3 is 0.031 μm, and the inner surface roughness Ra of the mold in Comparative Example 4 is 4.045 μm.

[0117] Comparative Example 5

[0118] The preparation method of the curved microcrystalline panel provided in this comparative example is basically the same as that of Example 1, except that, in step (2), a curved iron-based mold (without auxiliary side edges) is used instead of a refractory mold.

[0119] Table 1 Differences in parameters of each group

[0120]

[0121]

[0122] Table 2 Differences in parameters of each group

[0123]

[0124] It can be seen from Table 1 and Table 2 that the curved micro-ceramic glass plate prepared in each embodiment has a smooth surface, good flatness, no surface scratches, a central angle greater than 114°, and a low thermal expansion coefficient.

[0125] In contrast, the maximum thickness of the mold in Comparative Example 1 is 25 mm, which results in a significant increase in radial and axial unevenness, and a relatively high A value and B value.

[0126] α in Comparative Example 2 does not satisfy >(21750-2490000 / θ) 1 / 2 , resulting in multiple scratches on the surface of the curved micro-ceramic glass plate.

[0127] The roughness of the inner surface of the mold in Comparative Example 3 is too low, resulting in multiple delaminations on the outer surface of the curved microcrystalline glass plate (the contact surface with the mold). This is because the microcrystalline original plate is adsorbed by the mold, resulting in abnormal molding and failure to fit the mold.

[0128] The inner surface roughness of the mold in Comparative Example 4 is too high, and small particles on the mold surface fall off during the crystallization process, resulting in multiple white spots on the outer surface of the curved microcrystalline glass plate. Such defects must be removed through subsequent mechanical processing, which does not meet the requirement of the present invention that no subsequent processing is required.

[0129] Furthermore, the use of an iron-based mold without auxiliary side edges in Comparative Example 5 resulted in significantly increased radial unevenness, with a radial unevenness A of 1.70%. Furthermore, the use of an iron-based mold in Comparative Example 5 inevitably resulted in a large amount of debris generated during the heating process due to high-temperature oxidation, which remained between the microcrystalline panel and the mold. Although the debris itself easily fell off the microcrystalline panel surface, it caused small pits to appear on the interface between the microcrystalline panel and the mold, significantly increasing the outer surface roughness.

[0130] Although the present invention has been illustrated and described using specific embodiments, it should be appreciated that the above embodiments are merely intended to illustrate the technical solutions of the present invention rather than to limit them. Those skilled in the art should understand that the technical solutions described in the above embodiments may be modified, or some or all of the technical features thereof may be replaced by equivalents, without departing from the spirit and scope of the present invention. However, these modifications or replacements do not deviate from the essence of the corresponding technical solutions within the scope of the technical solutions of the embodiments of the present invention. Therefore, this means that all such replacements and modifications within the scope of the present invention are included in the appended claims.

Claims

1. A curved glass-ceramic plate, characterized in that: The roughness of the inner surface of the curved glass-ceramic plate is ≤0.06 μm, and the roughness of the outer surface of the curved glass-ceramic plate is ≤0.06 μm; The shape of the curved glass-ceramic plate is an arc; The radial unevenness A of the curved glass-ceramic plate is ≤ 0.4%, where A = h / L × 100%. When the curved glass-ceramic plate is placed on a horizontal plane with its opening facing downward, three vertices of the curved glass-ceramic plate are in contact with the horizontal plane, and the distance from the other vertex to the horizontal plane is h. L is the length of the curved glass-ceramic plate in the axial direction. The units of h and L are the same. The axial unevenness B of the curved glass-ceramic plate is ≤ 0.4%, where B = d / L × 100%. When the curved glass-ceramic plate is placed on a horizontal surface with its opening facing downward, the top end of the curved glass-ceramic plate bends downward along the axial direction of the curved glass-ceramic plate to form a curved arc, and the maximum distance between the curved arc and the line connecting the midpoints of the two curved sides of the curved glass-ceramic plate is d. L is the length of the curved glass-ceramic plate along the axial direction; the units of d and L are the same. The thermal expansion coefficient of the curved microcrystalline glass plate at a temperature of 40 to 700° C. is less than 0.5 ppm / ° C.

2. The method for preparing a curved glass-ceramic plate according to claim 1, wherein: The steps include: Obtain a double-sided polished flat microcrystalline original plate; The double-sided polished flat microcrystalline original plate is placed on a refractory material mold and then subjected to heat treatment for shaping and crystallization to obtain the curved microcrystalline glass plate.

3. The method for preparing a curved glass-ceramic plate according to claim 2, wherein: The vertices and four sides of the double-sided polished flat microcrystalline original plate are chamfered and / or rounded.

4. The method for preparing a curved glass-ceramic plate according to claim 2, wherein: The material of the flat-plate microcrystalline original plate includes LAS microcrystalline glass.

5. The method for preparing a curved glass-ceramic plate according to claim 2, wherein: The refractory material in the refractory mold includes at least one of a zirconium refractory material, a corundum refractory material, a magnesia refractory material, a calcium-magnesia refractory material and a silicon refractory material.

6. The method for preparing a curved glass-ceramic plate according to claim 2, wherein: The thickness of the refractory material mold is ≤15mm.

7. The method for preparing a curved glass-ceramic plate according to claim 2, wherein: The roughness of the inner surface of the refractory material mold is 0.05-4.00 μm.

8. The method for preparing a curved glass-ceramic plate according to claim 2, wherein: The central angle of the curved glass-ceramic plate is greater than 114°.

9. The method for preparing a curved glass-ceramic plate according to claim 8, wherein: The refractory mold is in an arc shape; the refractory mold is connected to auxiliary side edges on two sides along its axial direction, and the auxiliary side edges are in a flat plate shape. The refractory mold is fixedly connected or detachably connected to the two auxiliary side edges. When the refractory mold is placed with its opening facing upward, the angle α between the auxiliary side edges and the horizontal plane satisfies: α>(21750-2490000 / θ) 1 / 2 , where θ is the central angle of the curved glass-ceramic plate, in degrees.

10. Application of the curved glass-ceramic plate as claimed in claim 1 in the fields of architecture and decoration.

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